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Subject[PATCH] usb: gadget: Add the console support for usb-to-serial port
Date
It dose not work when we want to use the usb-to-serial port based
on one usb gadget as a console. Thus this patch adds the console
initialization to support this request.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
drivers/usb/gadget/Kconfig | 6 +
drivers/usb/gadget/function/u_serial.c | 238 ++++++++++++++++++++++++++++++++
2 files changed, 244 insertions(+)

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index 33834aa..be5aab9 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -127,6 +127,12 @@ config USB_GADGET_STORAGE_NUM_BUFFERS
a module parameter as well.
If unsure, say 2.

+config U_SERIAL_CONSOLE
+ bool "Serial gadget console support"
+ depends on USB_G_SERIAL
+ help
+ It supports the serial gadget can be used as a console.
+
source "drivers/usb/gadget/udc/Kconfig"

#
diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c
index f7771d8..4ade527 100644
--- a/drivers/usb/gadget/function/u_serial.c
+++ b/drivers/usb/gadget/function/u_serial.c
@@ -27,6 +27,7 @@
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/module.h>
+#include <linux/console.h>

#include "u_serial.h"

@@ -79,6 +80,16 @@
*/
#define QUEUE_SIZE 16
#define WRITE_BUF_SIZE 8192 /* TX only */
+#define GS_BUFFER_SIZE (4096)
+#define GS_CONSOLE_BUF_SIZE (2 * GS_BUFFER_SIZE)
+
+struct gscons_info {
+ struct gs_port *port;
+ struct tty_driver *tty_driver;
+ struct work_struct work;
+ int buf_tail;
+ char buf[GS_CONSOLE_BUF_SIZE];
+};

/* circular buffer */
struct gs_buf {
@@ -118,6 +129,7 @@ struct gs_port {

/* REVISIT this state ... */
struct usb_cdc_line_coding port_line_coding; /* 8-N-1 etc */
+ struct usb_request *console_req;
};

static struct portmaster {
@@ -1054,6 +1066,7 @@ gs_port_alloc(unsigned port_num, struct usb_cdc_line_coding *coding)

port->port_num = port_num;
port->port_line_coding = *coding;
+ port->console_req = NULL;

ports[port_num].port = port;
out:
@@ -1143,6 +1156,227 @@ err:
}
EXPORT_SYMBOL_GPL(gserial_alloc_line);

+#ifdef CONFIG_U_SERIAL_CONSOLE
+
+static struct usb_request *gs_request_new(struct usb_ep *ep, int buffer_size)
+{
+ struct usb_request *req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+
+ if (!req)
+ return NULL;
+
+ /* now allocate buffers for the requests */
+ req->buf = kmalloc(buffer_size, GFP_ATOMIC);
+ if (!req->buf) {
+ usb_ep_free_request(ep, req);
+ return NULL;
+ }
+
+ return req;
+}
+
+static void gs_request_free(struct usb_request *req, struct usb_ep *ep)
+{
+ if (req) {
+ kfree(req->buf);
+ usb_ep_free_request(ep, req);
+ }
+}
+
+static void gs_complete_out(struct usb_ep *ep, struct usb_request *req)
+{
+ if (req->status != 0 && req->status != -ECONNRESET)
+ return;
+}
+
+static struct console gserial_cons;
+static int gs_console_connect(void)
+{
+ struct gscons_info *info = gserial_cons.data;
+ int port_num = gserial_cons.index;
+ struct usb_request *req;
+ struct gs_port *port;
+ struct usb_ep *ep;
+
+ if (port_num >= MAX_U_SERIAL_PORTS || port_num < 0) {
+ pr_err("%s: port num [%d] exceeds the range.\n",
+ __func__, port_num);
+ return -ENXIO;
+ }
+
+ port = ports[port_num].port;
+ if (!port) {
+ pr_err("%s: serial line [%d] not allocated.\n",
+ __func__, port_num);
+ return -ENODEV;
+ }
+
+ if (!port->port_usb) {
+ pr_err("%s: no port usb.\n", __func__);
+ return -ENODEV;
+ }
+
+ ep = port->port_usb->in;
+ if (!ep) {
+ pr_err("%s: no usb endpoint.\n", __func__);
+ return -ENXIO;
+ }
+
+ req = port->console_req;
+ if (!req) {
+ req = gs_request_new(ep, GS_BUFFER_SIZE);
+ if (!req) {
+ pr_err("%s: request fail.\n", __func__);
+ return -ENOMEM;
+ }
+ req->complete = gs_complete_out;
+ }
+
+ info->port = port;
+
+ pr_debug("%s: port[%d] console connect!\n", __func__, port_num);
+ return 0;
+}
+
+static void gs_console_work(struct work_struct *work)
+{
+ struct gscons_info *info = container_of(work, struct gscons_info, work);
+ struct gs_port *port = info->port;
+ struct usb_request *req;
+ struct usb_ep *ep;
+ int xfer, ret, count;
+ char *p;
+
+ if (!port || !port->port_usb)
+ return;
+
+ req = port->console_req;
+ ep = port->port_usb->in;
+ if (!req || !ep)
+ return;
+
+ spin_lock_irq(&port->port_lock);
+ count = info->buf_tail;
+ p = info->buf;
+
+ while (count > 0 && !port->write_busy) {
+ if (count > GS_BUFFER_SIZE)
+ xfer = GS_BUFFER_SIZE;
+ else
+ xfer = count;
+
+ memcpy(req->buf, p, xfer);
+ req->length = xfer;
+
+ port->write_busy = true;
+ spin_unlock(&port->port_lock);
+ ret = usb_ep_queue(ep, req, GFP_ATOMIC);
+ spin_lock(&port->port_lock);
+ port->write_busy = false;
+ if (ret < 0)
+ break;
+
+ p += xfer;
+ count -= xfer;
+ }
+
+ info->buf_tail -= count;
+ spin_unlock_irq(&port->port_lock);
+}
+
+static int gs_console_setup(struct console *co, char *options)
+{
+ struct gscons_info *gscons_info;
+
+ gscons_info = kzalloc(sizeof(struct gscons_info), GFP_KERNEL);
+ if (!gscons_info)
+ return -ENOMEM;
+
+ gscons_info->port = NULL;
+ gscons_info->tty_driver = gs_tty_driver;
+ INIT_WORK(&gscons_info->work, gs_console_work);
+ gscons_info->buf_tail = 0;
+ co->data = gscons_info;
+
+ return 0;
+}
+
+static void gs_console_write(struct console *co,
+ const char *buf, unsigned count)
+{
+ struct gscons_info *info = co->data;
+ int avail, xfer;
+ char *p;
+
+ avail = GS_CONSOLE_BUF_SIZE - info->buf_tail;
+ if (count > avail)
+ xfer = avail;
+ else
+ xfer = count;
+
+ p = &info->buf[info->buf_tail];
+ memcpy(p, buf, xfer);
+ info->buf_tail += xfer;
+
+ schedule_work(&info->work);
+}
+
+static struct tty_driver *gs_console_device(struct console *co, int *index)
+{
+ struct gscons_info *info = co->data;
+
+ *index = co->index;
+ return info->tty_driver;
+}
+
+static struct console gserial_cons = {
+ .name = "ttyGS",
+ .write = gs_console_write,
+ .device = gs_console_device,
+ .setup = gs_console_setup,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+};
+
+static void gserial_console_init(void)
+{
+ register_console(&gserial_cons);
+}
+
+static void gserial_console_exit(void)
+{
+ struct gscons_info *info = gserial_cons.data;
+ struct gs_port *port = info->port;
+ struct usb_request *req;
+ struct usb_ep *ep;
+
+ if (port && port->port_usb) {
+ req = port->console_req;
+ ep = port->port_usb->in;
+ gs_request_free(req, ep);
+ }
+
+ kfree(info);
+ unregister_console(&gserial_cons);
+}
+
+#else
+
+static int gs_console_connect(void)
+{
+ return 0;
+}
+
+static void gserial_console_init(void)
+{
+}
+
+static void gserial_console_exit(void)
+{
+}
+
+#endif
+
/**
* gserial_connect - notify TTY I/O glue that USB link is active
* @gser: the function, set up with endpoints and descriptors
@@ -1219,6 +1453,7 @@ int gserial_connect(struct gserial *gser, u8 port_num)
gser->disconnect(gser);
}

+ status = gs_console_connect();
spin_unlock_irqrestore(&port->port_lock, flags);

return status;
@@ -1320,6 +1555,8 @@ static int userial_init(void)
goto fail;
}

+ gserial_console_init();
+
pr_debug("%s: registered %d ttyGS* device%s\n", __func__,
MAX_U_SERIAL_PORTS,
(MAX_U_SERIAL_PORTS == 1) ? "" : "s");
@@ -1334,6 +1571,7 @@ module_init(userial_init);

static void userial_cleanup(void)
{
+ gserial_console_exit();
tty_unregister_driver(gs_tty_driver);
put_tty_driver(gs_tty_driver);
gs_tty_driver = NULL;
--
1.7.9.5


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